Chromosome 19 (CH19) comprises approximately 2.1% of the human genome. Several diseases (e.g. , myotonic muscular dystrophy, malignant hyperthermia) have been localized to this area and the regions around these disorders have been well characterized and mapped. The accumulation of both physical and genetic markers over the entire length of CH19 has been relatively slow. Considerable effort is now being made by several groups to generate additional CH19 markers. As these new markers become available, the ability to construct complete and comprehensive maps of CH19 is possible. The purpose of this workshop is to compile and consolidate the available genetic and physical mapping data from the various laboratories. These individual maps will then be used as a basis to produce a consensus map for the chromosome. Through the workshop efforts, we will be able to identify problem areas that need additional data as well as areas of overlap. In addition, we will identify inconsistencies in the maps. The conference, to be held in Charleston, South Carolina, will be formatted such that each group represented will give a short presentation of their data. All aspects of mapping will be covered including both physical mapping and genetic mapping studies. The individual presentations will be followed by workshop sessions whose emphasis will be to generate a consensus CH19 map and to delineate areas for future concentration. The data will be compiled for the CH19 committee (Drs. Hans-Hilger Ropers and Pericak-Vance) for HGM10.5 and 11 for incorporation into the committee report.